Summary of Work: Age at menopause has been proposed as a marker of aging and health. We are examining the association between age at natural menopause and mortality in a population-based sample of women in the United States. This study is based on data from the National Health and Examination Survey (NHANES) Epidemiologic Follow-up Study; 2,562 women ages 50 to 86 were included, 299 deaths occurred over a mean follow-up time of 4.0 years. Compared with women who were menstruating at least to age 50, the adjusted rate ratio (RR) was 1.51 (95% confidence interval, CI, (0.97-2.35)) for women with a natural menopause at age < 40, 1.06 (95% CI (0.73-1.53)) for menopause ages 40-44, and 0.96 (95% CI (0.72- 1.26) for menopause ages 45-49. Age at menopause has also been proposed as a marker of ovarian toxicity for factors which may directly or indirectly damage the follicular pool. Several rare genetic conditions result in early ovarian failure, and smoking has been consistently shown to decrease age at menopause. However, the literature on causes of early ovarian failure is quite limited. We are developing a population-based case-control study of early ovarian failure to address specific hypotheses concerning familial and environmental risk factors, including environmental tobacco smoke, galactose consumption and metabolism, and organochlorine pesticide exposure. We will also examine menstrual, reproductive, and medical history, particularly with respect to autoimmune diseases, as risk factors for early ovarian failure.